power consumption after shutdown

Richard A. Smith richard at laptop.org
Mon Feb 16 00:19:41 EST 2009

quozl at laptop.org wrote:

> (If one discharges an XO battery outside the XO using a home lighting
> circuit, the displayed state of charge will be inconsistent.  Persisting
> in this practice results in increasing inconsistency.  Ceasing the
> practice results in decreasing inconsistency over several XO moderated
> charge and discharge cycles.  The inconsistency results in forced
> power-down before the state of charge would suggest, manifesting as "my
> XO stops too soon".)

How far off is it?  The EC actually tries to detect this.  The ACR 
register will decrease when you use the battery outside the laptop.

The EC periodically takes a snapshot of the SOC and the current ACR and 
saves it into the EEPROM.  When you insert a battery the first thing it 
does is compare the current ACR vs the saved values and then roll the 
SOC up or down depending on the difference between the values.

Richard Smith  <richard at laptop.org>
One Laptop Per Child

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